1. Field of the Invention
The present invention relates to a steering device.
2. Description of the Related Art
A rack-parallel electric power steering device is known as one type of steering devices for vehicles. The rack-parallel electric power steering device includes a ball screw device attached to the outer periphery of a rack shaft, a motor with an output shaft disposed in parallel with the rack shaft, and a speed reducer that couples the output shaft of the motor and the ball screw device to each other. The periphery of the speed reducer is covered by a housing.
In the rack-parallel electric power steering device, when water enters the housing from the outside and the water resides in the housing, the speed reducer may be flooded with the water. When the water in the housing is frozen with the speed reducer flooded with water, operation of the speed reducer is hindered. When operation of the rack shaft coupled to the speed reducer via the ball screw device is hindered, a steering feel may be deteriorated by a heavy steering operation or the like. Thus, there has hitherto been known a steering device in which a drain valve is provided at a bottom wall portion of a housing under a speed reducer in the vertical direction in order to discharge water having entered the housing. An example of such a drain valve is described in German Patent Application Publication No. 10 2009 039 832.
As illustrated in FIG. 11, a drain valve 100 described in German Patent Application Publication No. 10 2009 039 832 includes a case body 101 in a bottomed cylindrical shape, and a valve element 102 housed inside the case body 101. The case body 101 is structured such that a second case 104 in a bottomed cylindrical shape is assembled to an end portion of a cylindrical first case 103. A cylindrical attachment portion 103a is formed at the center portion of an opening portion of the first case 103 on the second case 104 side. A valve seat 103b which is an annular projecting portion is formed at an end surface of the first case 103 on the second case 104 side. A discharge hole 104a that penetrates from the inside to the outside is formed in the bottom portion of the second case 104. The valve element 102 is a disc-shaped elastic member. A projecting portion 102a is formed at the center portion of the valve element 102. The projecting portion 102a engages with the attachment portion 103a of the first case 103 so that the valve element 102 is fixed with respect to the first case 103. The peripheral edge portion of the valve element 102 closely contacts the valve seat 103b of the first case 103. In the drain valve 100, water having entered a housing (not illustrated) flows into the first case 103 through an opening portion 103c of the first case 103, and is discharged to the outside of the housing via the valve element 102 and the discharge hole 104a. In the case where water enters the second case 104 from the outside of the housing via the discharge hole 104a, on the other hand, the valve element 102 suppresses inflow of the water into the housing.
In the drain valve 100 described in German Patent Application Publication No. 10 2009 039 832, in order to fix the valve element 102 to the first case 103, it is necessary to form the first case 103 with the attachment portion 103a, and form the valve element 102 with the projecting portion 102a. This incurs complication of the structure of the drain valve 100.